Welcome to
LG LCD TV
LE-15A10
LL-15A10
Europe
Africa
CIS
Middle-East
LT-15A10
China
Asia
Canada
America
Taiwan
Philippines
Austria
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Contents
1. LCD Technology
1) What is TFT LCD ?
2) Structure of TFT LCD
3) TFT-LCD Operating Mechanism
4) Operating Theor y
5) Structure LCD Module
6) Structure of Back light
7) Function of Back light
8) Key Parts ; Color Filter, Polarizer
2. LCD Market Trend
(1) Comparison with other Displa y devices
(2) World Display Market Trend
(3) LCD TV Market trend
(4) Guidance of handling LCD product
(5) Abbreviations
3. LCD TV Structure
(1) General Specifications
(2) Presentation for SVC Engineer
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1. LCD Technology
1) What is TFT LCD ?
2) Structure of TFT LCD
3) TFT-LCD Operating Mechanism
4) Operating Theor y
5) Structure LCD Module
6) Structure of Back light
7) Function of Back light
8) Key Parts ; Color Filter, Polarizer
3
What is TFT(Thin Film Transistor)?
TRANSISTOR
(MOS-FET)
DRAIN
V
th
GATE
SOURCE
When supply over certain voltage(Vth) to
the GATE, it delivers information from
Drain to Source
SWITCHING Characteristics
TFT Panel
TFT Element
TFT
DRAIN
V
th
GATE
SOURCE
TPE
Compound Transistor with thin film in every Pixel
on ITO.
Independent on neighboring Pixel
TFT Cross section
Semi-Conductor
Insulator
Transparent Pixel Electrode
SOURCE DRAIN
GATE
Glass Panel
4
Structure of TFT- LCD
%
% (Approx....)
300
%%
One Pixel
)
Common Electrode
)
Pixel Electrode
Data Line
Gate Line
!
! Liquid Crystal
!!
Control the amount
of light by the
Applying Voltage
C/F Glass
TFT Glass
TFT LCD
Panel
#
# Source
##
Transport the
Data Signal
Glass
+ + + +
-
- -
+
"
" Gate
""
On/Off the
TFT
Glass
Back Light
-
- -
$
$ Pixel
$$
Applying
Voltage
to the
Liquid Crystal
Polarizer
Liquid
Crystal
- - - - - -
White (TFT Off) Black (TFT On)
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TFT- LCD Operating mechan is m
The structure of TFT-LCD is that Liquid Crystal is being filled betw een C/F Glass & TFT Glass. One Pixel consists of 3
sub-Pixels(R,G,B) and according to the number of the pixels, Display Resolution (SVGA,XGA,etc) is determined.
The TFT Matrix consists of Data Line(Carrying display data signal),Gate Line(Carrying signal for turn On/Off the
TFT).Each TFT, on each sub-pixel, controls the amount of Applying Voltage between C/F glass electrode & TFT glass
electrode for the Liquid Crystal.
The Applying Voltage changes the Direction of Liquid Crystal w hich changes direction of the Light. Transmittance rate
of the Polarized Light, polarized by Polarizer, is controlled by Applying Voltage. As a conclusion, Displayed Light is now
under-control of Display Data Signal.
Light(CCFL lamp)
Polarizer is a filter
Polarizer
which polarize the
light to one direction.
Liquid
Crystal
< Light transmittance >
< Blocking >
Polarized light
Electrode
&&&&
V
LC
= off
V
LC
= on
&&&&
Liquid
Crystal
Electrode
< VLC = 0 > < VLC = 3.3V >
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Operating Theory
(Braun Tube : Light Emitting Component) (TFT-LCD : Non-Light Emitting Component)
HEATER
Electronic Gun
Grid 1
Grid 2
Grid 3
Anode
Grid 4
Deflection
Section
GLASS
Flourescent
Beam
Vacuum
Luminous
Source
Polarizer
Light(White)
COLOR FILTER
Glass Panel
Polarizer
Liquid
Crystal
Green
TFT+Electrode
Electrode
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Structure of LCD Module
LCM = Case top + LCD panel
B/L Assy + Plate
Case Top
LCD Panel
Diffusers & Prisms
Light Guide
Reflector
Lamp
Housing Lamp
D-IC(on TCP)
PCB
Support Main
Bottom Cover
#
"
$
Back light
Assy
!
Bottom Plate
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Structure of LCD Module
Driving
Circuit
Bright Dark Gray
Gate Driver IC
Inverter
Power Supply
for Video Signal
Data Driver IC
Printed PCB Board
Pixel Array & Wiring
Common
Electrode
Lamp
Dn-1
R
Dn
Dn+1
Polarizer
CF Panel
LC
TFT Panel
Polarizer
G
B
Pixel Electrode
LC Panel
LC
Lamp
Inverter
Lamp
Prism
Diffuser
Light Guide
Reflector
B/L Unit
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Structure of Back Light Unit
Pad
Diffuser(Protector)
Top Prism
Bottom Prism
Diffuser
Light Guide
Screw
Plate
Reflector
Supporter main
Lamp Housing
Lamp Ass
y
’
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Function of Back Light
Structure of B ack Light
Lamp
LCD PANEL
Diffuser
(Protector)
Top Prism
Bottom Prism
Diffuser
Function on each part
Display the light controlled by data signal
Same structure as bellow diffuser, Protect the
top prism
Same function as bottom prism, Increase the
luminanc e up to 1.3 3 ti mes o f bott o m pri s m
Concentrate the light and increase the luminance
up to 1.55 times of the light guide
Uniform and concentrate the light received
from light guide
Lamp Housing(Lamp Reflector)
Pattern(Dot/Shibo/V-cut)
Light guide
(Flat/Wedge)
Reflector
Guide the light from lamp and uniform the light
Reflect the leakage light from light guide to reduce
the loss of the light injected to the light guide
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Key Parts : Color Filter
To realize color of the Display, array Red,Green & Blue color paint beneath Upper Glass Panel regularly in
accord with Pixel electrode of lower Glass Panel.
! Kinds of Pixel Array
' Delta Array
( Stripe Arra y
! The Function of Color Filter
Divide the white light from luminous source into Red, Green & Blue
Pixel
White Light
) Mosaic Array
Common Electrode
Glass
BRG
12
Key Parts : Polarizer
A kind of filter, which polarize light one direction.
Light
Polarizer
<Passing>
<Blocking>
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Key Parts : Back Light
Back Light Unit,located behind TFT-Panel lower Glass, and supplies light to the PANEL.
CCFL LAMP
(Cold Cathode Fluorescence Lamp)
LAMP
AC 1000V
Inverter
Direct Type
Structure
LAMP
LCD Panel
CASE
Can realize White Light
Long life time(Appr. 25,000HRS)
Simple Brightness control
Small Size
Easy to Adhere
Side Guided Type
LCD Panel
Guide
LAMP
Reflector
Merits
Demerits
High Light Efficiency
Simple Structure
Thick
Slim & Compact Size
Complicated Structure,Expensive
Low Light Efficiency
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